Extinguishing device for electrical arcs



United States Patent Ofiice 3,127,490 Patented Mar; 31, '1964 3,127,490EXTINGUISHING DEVICE FOR ELECTRICAL ARCS Andr Latour, Grenoble, France,assignor to Etablissemeats Merlin & Gerin, S.A., Grenoble, France FiledJuly 3, 1961, Ser. No. 121,432 Claims priority, application France July1, 1960 4 Claims. (Cl. 200144) This invention relates to extinguishingdevices for electrical arcs drawn between separable contact memberslocated in an arc formation chamber of an electrical circuit breaker,and more particularly to extinguishing devices of this type having anarc extinguishing chamber which comprises a set of at least two parallelplates of insulating material spaced apart from one another and disposedtransversely of the direction of separation of the contacts in theinitial direction of the arc.

The spaced parallel plates of insulating material define narrow arcseparating or extinguishing chambers and are provided with conductivemembers to form branches which are generally V- or U-shaped and whoselegs or wings embrace or straddle the individual insulating plates.Conductive members of this general type and configuration are disclosedin my U.S. Patent No. 2,707,739. The web portion of the V- or U-shapedconductive member straddles the side or edge of an insulating platewhile the legs or wings of the conductive member extend along the facesof the insulating plates in a substantially parallel arrangement. Theopposed parallel wings of each conductive member are slightly offset ordiverging relative to each other. The insulating plates are providedwith marginal spacing members or ribs by means of which individualplates may be stacked together to form a set. These marginal ribsprovide also a proper spacing of the plates to accommodate theconductive elements in the spaces between adjacent plates and alsodefine indlvidual chambers into which the initial are or are portionsare drawn. The are travels along the inner edges of the V-shapedconductive members and is caused to form peripherally expanding loops inthe spaces between the lates.

p It is known that during the development or expansion of the arcs anarcing over is occasionally produced between neighboring electrodes orconductive members, particularly when the voltage of the arc reaches acertain magnitude. In known arrangements of this type these arcingphenomena take place at the base or the web portion of the conductivemember which interconnects the two legs or wings of each conductivemember. As the web portions of the conductive members engage the loweredge of the insulating plates, this arcing occurs therefore almostoutside the arc extinguishing chambers.

According to the invention the conductive members are connected to theinsulating plates at two different horizontal levels and in a set of aplurality of consecutively stacked insulating plates. A plate having aconductive member disposed at a different level is always interposedbetween two plates carrying a conductive member at the same level.

According to an additional feature of the present invention theconductive members which in the embodiment shown and described hereinare connected at the lower edge of the insulating plate or which formthe lower level conductive members have such a form that the point atwhich the electrical rigidity between two successive conductive membersis at a minimum, is not located at the base of the insulating plates buton the inside of the extinguishing chambers. The path of the currentwhich passes through the conductive members at the time the arcing overtakes place assures, due to the formation of spiral convolutions, anelectrodynamic effect which is already intense and which is favorablefor driving the initial are or are portions upwardly into the arcextinguishing chambers. It is therefore an object of the presentinvention to provide an arc extinguishing device in which the arcingover occuring between adjacent conductive members is moved upwardly intothe interior of the extinguishing ci ambers.

It is another object of the present invention to provide an arcextinguishing device in which the conductive members connected to theinsulating plates are arranged to produce an electrodynamic effect onthe arcing over between adjacent conductive members and thereby drivethe initial arcs eifectively upward into the extinguishing chamberswhere they are extended and extinguished in a quick and efficientmanner.

These and other objects of the invention will become apparent uponreading the specific description in connection with the accompanyingdrawing which forms part of the specification and which by way ofexample illus trates an embodiment of the invention. The embodimentsdisclosed in the drawing and described in the specification are to beunderstood to serve only to explain the invention but not to limit itsscope. Other embodiments incorporating the principle underlying theinvention are feasible without departing from the spirit and scope ofthe appended claims. In the drawings:

FIGURE 1 is a front view in elevation of an insulating plate providedwith a conductive member connected with its base or web portion at alower level along the lower edge of the insulating plate.

FIGURE 2 shows a front view in elevation of an in sulating platemodified relative to the insulating plate shown in FIG. 1 in which thebase or web portion of the conductive member is located at a higherlevel upwardly from the lower edge of the insulating plate.

FIG. 3 shows a front view of the lower part of a subassembly of theextinguishing device of the invention comprising a set of three stackedinsulating plates.

FIG. 4 shows a cross-section through the axis of the arc extinguishingdevice along line 4-4 of FIG. 3.

Referring now more particularly to the drawings the arc extinguishingdevice which consists of a set of stacked insulating plates of two typesdesignated by numerals 1 and 2 are disposed in such a manner relative toeach other within the same set that each plate of one type is locatedbetween two plates of the other type. Each of the insulating plates isprovided in a known manner with a peripheral flange or rib 11 whichconstitutes the spacing means between successive insulating plates andwhich limits the extension of the loops formed by the initial arcs ofthe arc extinguishing operation. The spaced insulating plates define thearc extinguishing chamber into which the initial arcs are drawn andextinguished. The spacing ribs 11 are provided with a groove 12 in whicha sealing member is arranged to thereby provide a tight seal betweenadjacent insulating plates. Vertical parallel ribs 13 are provided onthe upper part of the insulating plates and define discharge or exhaustchannels for the ionized gases which develop during the circuit breakingand are extinguishing operation. The upper part of the insulating plateis shown and described merely for the purpose of explanation and doesnot form a part of the present invention. The lower edge of insulatingplate 1 is embraced or straddled by conductive member 14 which comprisestwo legs or wings 15 and 16 located on opposite faces of the insulatingplate. The two wings are interconnected by a web portion 17 whichengages a slightly cutout section along the lower edge of the insulatingplate. The conductive members 14 which are connected at the lower edgeof the associated insulating plate are particularly distinctive in thateach wing has an inwardly extending curvilinear recess 18.

Theinsulating plates 2 are also provided with conductive membersdesignated by reference numeral 19 and comprising each two legs or wings20 and 21 located along each face of the insulating plate. The two wingsare interconnected by a base or web portion 22 which engages theinsulating plate at the top of a substantially triangular notch 23formed in the insulating plate 2. The conductive members 14 and 19extend into close proximity of the vertical ribs 13 and as theconductive members 19 start only at the top of the triangular notch inthe insulating plates they are not as long as conductive members 14which start at the lower edge of the associated insulating plates.

Referring to FIGS. 1 and 2 of they drawing it will be observed that thepoint of two successive conductive members located in the sameextinguishingchamber at which the spacing or interval is at a minimum islocated at 24 with reference to Wings 16 and 2t) and at 25 withreference to wings 15 and 25, and at the levels'24 and 25 the dielectricresistance of the conductive members is at a minimum and it is therethat the arcing over between successive conductive members takes place.The tendency to are over is sometimes increased and accelerated by thepresence of ionized gases which are produced by the initial arc. Thepath of the lines of current in the conductive members have the form ofspiral convolutions and several such lines of current interconnected byarcing over constitute a solenoid which has the efiect of urging ordriving the arcs upwardly into the extinguishing chambers. Thecurvilinear recesses 18 provided in conductive members 14 contributealso effectively to the formation of such solenoid effects. Thevertically upward displacement of the conductive members to the top ofthe notched portions. provide an additional upward pull on the initialarcs.

What is claimed is:

1. In a device for extinguishing an electric arc drawn between separablecontact members, first insulating plates having on each of two opposedfaces conductive means connected to each other at the lower end of saidplates and extending upwardly to a predetermined level, secondinsulating plates having a notched portion extending upwardly from thelower edge of said second plates, each second plate being disposedbetween two adjacent first plates, said first and said second platesbeing disposed face to face and transversely of the established arc,conductive members connected to said second insulating plates andextending upwardly from the inner end of the notched portions andspacing means between two successive insulating plates forspacing saidplates relative to each other and forming an arc chute.

2. In a device for extinguishing an electric arc to be drawn betweenseparable contact members, first insulating plates having on each of twoopposed faces conductive means connected to each other at the lower endof said plates and extending upwardly to a predetermined level, secondinsulating plates having a notched portion extending upwardly from thelower edge thereof, each second plate being disposed between twoadjacent first plates, said first and said second plates being disposedface to face and transversely of the established arc, an upwardlyextending conductive member connected to said notched insulating platesat the top edge of said notched portions, spacing members betweenadjacent insulating plates to form a chambered space between saidplates, said conductive members on said first insulating plates having arecess surrounding the base portion of the conductive member of saidsecond insulating plates to provide a point of least dielectricresistance between the conductive means in each space between adjacentplates and located above the base portion of the conductive members ofsaid second insulating plates to draw the are upwardly between saidinsulating plates.

3. A device as defined in claim 2 wherein theconductive members of saidfirst insulating plates are longer than the conductive members of saidsecond insulating plates so as to extend upwardly along the faces ofsaid plates substantially even with the conductive members of saidsecond insulating plates.

4. In an arc extinction chamber comprising a first plurality of parallelplates of insulating material disposed transversely of the direction ofthe initial arc to be extinguished, conductive means on each of twoopposed faces of each plate connected to each other at the lower edge ofsaid plates, said conductive means comprising branches extendingupwardly from the base of the plates to which they are connected, secondplates of insulating material having conductive means comprisingelectrically connected branches extending upwardly on the opposed facesof each second plate, each second plate being disposed between twoadjacent first named plates, spacing means between two successiveinsulating plates forming wall means to provide a chambered spacebetween said plates, said conductive means of said first and secondplates dividing said initial are into individual portions drawn into thespaces between two successive plates to turn said portions into aposition substantially parallel to said plates causing said portions toexpand until extinction, the lower portions of the conducting means ofeach second plate being disposed a distance apart above the level of thebases of said first named plates, each pair of branches in each of saidchambered spaces providing a point of minimum dielectric resistance,said second plates having a notched portion extending upwardly from thelower edge of said second plates, said branches of each of said secondplates being connected to each other at the inner end of the notchedportions,the apex of the notched portions confronting a point locatedunderneath said point of minimum dielectric resistance.

References Cited in the file of this patent UNITED STATES PATENTS2,750,476 Latour June 12, 1956 2,783,336 Latour Feb. 26, 1957 2,847,540Pfeiffer et al Aug. 12, 1958 2,868,927 Wood Jan. 13, 1959 FOREIGNPATENTS 715,121 Great Britain Sept. 8, 1954

1. IN A DEVICE FOR EXTINGUISHING AN ELECTRIC ARC DRAWN BETWEEN SEPARABLECONTACT MEMBERS, FIRST INSULATING PLATES HAVING ON EACH OF TWO OPPOSEDFACES CONDUCTIVE MEANS CONNECTED TO EACH OTHER AT THE LOWER END OF SAIDPLATES AND EXTENDING UPWARDLY TO A PREDETERMINED LEVEL, SECONDINSULATING PLATES HAVING A NOTCHED PORTION EXTENDING UPWARDLY FROM THELOWER EDGE OF SAID SECOND PLATES, EACH SECOND PLATE BEING DISPOSEDBETWEEN TWO ADJACENT FIRST PLATES, SAID FIRST AND SAID SECOND PLATESBEING DISPOSED FACE TO FACE AND TRANSVERSELY OF THE ESTABLISHED ARC,CONDUCTIVE MEMBER CONNECTED TO SAID SECOND INSULATING PLATES ANDEXTENDING UPWARDLY FROM THE INNER END OF THE NOTCHED PORTIONS ANDSPACING MEANS BETWEEN TWO SUCCESSIVE IN-